Typical designs for an infrared photodetector for a focal plane array comprise a “Barrier” layer of constant alloy composition, whose composition is specifically chosen to guarantee a near-zero valence-band offset in order to obtain high-efficiency collection of photogenerated minority carriers. The prior-art devices are optimized for high-efficiency collection of photogenerated charge in the bulk of the device, but fail to provide mechanisms to minimize the effects of surface recombination/generation in the periphery outside the influence of the semiconductor contact. This is especially critical for devices utilizing small (<25 μm) pixels with reduced junction areas in practical focal-plane arrays. The effect of the surface recombination/generation in the periphery shows up in the dark current.